A huge crowd is paying respect to the victims of yesterday's London attack

The memorial is being led by Mayor of London Sadiq Khan, who yesterday vowed the city would “not be cowed by terrorism”.

Huge crowds are now filling the famous square to listen to speeches and remember the victims of the attack.

Members of the public have used chalk to create messages of solidarity on the flood, including one which reads: "We are not afraid".

Three people were killed by terrorist Khalid Masood yesterday: PC Keith Palmer, who died stopping the attacker entering Parliament, US tourist Kurt Cochran, and mother-of-three Aysha Frade, who was killed as she walked to pick up her children from school.